This invention relates generally to portable electronic fish finding methods and systems, and particularly to buoys for fish finding methods and systems useable by fishermen along shorelines and river banks.
Sonar systems have long been used aboard water craft to detect shorelines, sea bottoms, sunken objects and marine life. More recently sonar based fish finders have been devised for use by fishermen from a river bank or a shore. Exemplary of these are those shown and described in U.S. Pat. Nos. 5,463,597; 5,495,689; 5,546,695; 5,887,376 and 6,122,852. These typically consist of a float or buoy that supports a sonar. The float is tethered as to a fishing pole. A transmission line extends from the float to a display screen that is located beside the shore based fisherman. With this system a fisherman is able to see sonar returns from fish and the immediate bottom terrain received and relayed from the buoy while standing on the bank. The buoy may be located over his or her baited fish hook or even be on the fishing line itself.
Unfortunately fish finders of the just described type have not gained substantial commercial acceptance. One of the main limitations of tethered transducers on the market today is a relatively short length of cable which limits the cast distance. Among their other limitations have been problems associated with rapid electric power exhaustion, the display of false and intermittent echoes, and with interference with similar units being used by other fishermen in the same locale. That both electrical transmission and fishing lines have extended between the float and shore has also been a complicating factor, particularly so where reels are used where line interference can easily occur. Even without reels line interference easily occurs as line tension and slack conditions change during fishing maneuvers.
Accordingly it is seen that a need remains for a portable fish finder for use by shore based anglers that consumes minimal power, that displays more reliable returns, and which can be simply set to avoid interference with another angler using even an identical fish finder in close proximity. It is to the provision of such that this invention is primarily directed.
In a preferred form of the invention a method of searching for marine life comprises the steps of generating a stream of digital electric sync pulses of a selected pulse length. Sonar pulses are transmitted from a buoyant station in response to sync pulse. Sonar echoes are received at the buoyant station and electric echo signals generated in response thereto. The electric echo signals are radio transmitted to a radio receiver at a shore station where those echo signals are displayed that follow a sync pulse.
In another preferred form of the invention, a buoy to shore fish finding system comprises a buoyant station having a sonar transmitter, a sonar receiver, a sonar to electric signal transducer and a radio transmitter all controlled by a microprocessor. A shore station has a radio receiver and signal display controlled by a shore station microprocessor. The buoyant station microprocessor is programmed to generate sync pulses and to transmit both the sync pulses and transduced sonar echo returns to the shore station. The shore station microprocessor is programmed to display only those echo signals received after a sync pulse.
The system buoyant station or buoy itself is of unique construction. It comprises a bulbous shell or capsule that houses a load and which has a center of mass located within a lower half of the shell. By half is meant generally half, not an exact mathematical or geometric half. The load includes sonar operatively linked via a microprocessor with a radio transmitter that has an upright antenna located in an upper half of the shell. The buoy also has means for tethering a fishing line to the shell which preferably is an eyelet formed in the buoy keel.